This invention relates to excavators for excavating and transplating trees.
A variety of different mechanisms have been developed for excavating trees and forming root balls to permit the trees to be transplanted.
U.S. Pat. No. 3,977,099 Stewart, discloses a digging maching which has a pair of spirical blades mounted for rotation. A parallelogram linkage is provided to effect rotation of the blades. The blades are separately mounted on the parallelogram linkage and are driven in an arcuate path from opposite sides of the tree in order to form the root ball. The mechanism is such that it is necessary for the parallelogram linkage mechanism to penetrate the soil in order to form the root ball and consequently this mechanism is subject to damage resulting from contact with obstacles in the soil.
U.S. Pat. No. 2,770,7076 (check number) Kluckhohn, discloses an excavator which excavates by forming a trench which extends from one side of the tree. As a result, the mechanism does not form a complete root ball, but merely serves to wrench the roots from the soil.
U.S. Pat. No. 2,990,630 discloses a free moving machine in which the excavator is formed in two halves which stradle the tree trunk during the excavation. This patent also discloses a structure in which the tree is transported with the trunk of the tree extending forwardly from the root ball toward the front end of the vehicle.
U.S. Pat. No. 4,045,891 Grew, discloses a structure in which the three blades are provided which serve to dig into the soil at circumferentially spaced intervals around the root ball.
U.S. Pat. No. 3,889,402 discloses an excavator in which two blades are mounted to move toward one another from opposite sides of the plant in order to form the root ball during the excavation operation.
U.S. Pat. No. 3,936,960 discloses a structure in which a plurality of spades are arranged to be driven downwardly into the soil so as to converge below the plant in order to form a root ball. A cutter blade is also provided which will extend under the spades in order to cut the tap root. The problem with this mechanism is that it does not fully support the root ball during the final excavation step of removing the tree.